Replying to Flashes, HELP

So i shoot on a d40x and was thinking about getting a flash, i need help on what flash to get, what accesories, and anything else. LIke if i got a sb 600, or whatever model thats compatible with my d40x, will i need anything else? and if I wanted to do wireless shooting so my camera isnt connected to my flash what would i need, I know stuff about nikons, but never have used external flash. Oh and what flash would you recommend, i wont be shooting that intensely, but i will be using it for skating as well. + k as always, please help. thanks.